Method of designing and producing a mold

ABSTRACT

A method of designing and producing a mold for manufacturing an article having at least one surface coated by a coating. The method including evaluating the article design to determine the probable flow characteristics of the mold, an optimal flow of the coating composition, and an optimal location for the coating composition injector. A mold is designed and produced based on the evaluation.

BACKGROUND OF THE INVENTION

The present invention relates to injection molding systems and the useof an in-mold coating (IMC) in these systems, more particularly to amethod for designing and producing a mold for use in connection with aninjection molding system having an IMC apparatus such that articlesproduced by the newly designed mold can be provided with a coating.

Molded thermoplastic or thermoset articles, such as those made frompolyolefins, polycarbonate, polyester, polyethylene, polypropylene,polystyrene and polyurethanes, are utilized in numerous applicationsincluding those for the automotive, marine, recreation, construction,office products, and outdoor equipment industries. Automotive industryapplications include, e.g., body panels, wheel covers, bumpers, head andtail lamps, fenders, hoods, and dashboards.

When the surface quality of molded articles does not meet requiredstandards such as those for durability, chemical resistance, and weatherresistance, or to facilitate paint adhesion, such articles must becoated.

Injection molding systems are used to produce thermoplastic or thermosetarticles. They allow a substrate-forming material (typically apelletized, granular or powdered plastic material fed from a hopper) tobe heated to a temperature above its melting or softening point and,using a filling pressure, injected into a closed mold maintained under aclamping pressure until the mold is substantially full; then, using apacking pressure, the mold is completely filled with thesubstrate-forming material to form a workpiece. The machine thenmaintains, under a mold or clamp pressure, the workpiece as it coolsuntil it can be removed from the mold without distortion. (The moldtypically is opened and closed either mechanically or hydraulically,usually using a predetermined timing cycle.) Such injection moldingprobably is the most widely used method of producing plastic parts.

Molds used in these systems generally have two parts, one of which isstationary and the other movable. The mold cavity formed by these halvesgenerally has a first surface on one mold half upon which a show orfinished surface of the molded article will be formed and acorresponding second surface on the other mold half. The stationary halftypically houses the cavity section of the mold and is mounted on astationary platen in contact with the injection section of the cylinderof the injection machine. The movable mold half typically holds the coreand ejector mechanism. Injection of substrate-forming material occursunder pressure when the mold is in a closed position. The clampingpressure, i.e., the pressure used to keep the mold closed duringinjection of the substrate-forming material, must be greater than thepressure used to inject that material.

SUMMARY OF THE INVENTION

A mold designed and produced according to the present method can be usedin a molding system capable of producing a molded article having atleast one surface to be coated. The system includes (i) a moldingmachine and (ii) a dispensing apparatus; the molding machine includes amold that includes first and second sections that are operable betweenopen and a closed conditions and that define a mold cavity in which themolded article is formed, and the dispensing apparatus can deliver acoating composition into the mold when the mold sections are closed.

The method of making a mold according to the present invention includes(a) evaluating the article and the surface(s) to be coated; (b)approximating the flow of the coating composition within the moldcavity; (c) determining a preferred location on the mold for at leastone nozzle through which the coating composition is injected into themold cavity; and (d) producing the mold sections that define the moldcavity shape from which the article can be formed, at least one of themold sections including an access port for each nozzle. Optionally, themethod can include the additional step of installing the nozzle(s) inthe appropriate mold section(s).

This method can include several optional variations. For example, themold can be modified to include at least one feature that modifies(i.e., enhances or restricts) flow of the coating composition. This flowacross the molded substrate can be modeled so as to determine optimalsettings for the molding machine and/or the dispensing apparatus, andthe mold design can be further modified based on the results of thisflow modeling.

Other optional additional steps also are possible. For example, apreferred substrate material and/or a preferred material for the coatingcomposition can be determined; an optimal mold temperature and/orsubstrate temperature for injecting the coating composition into themold can be determined; or at least one sensor can be mounted on themold for measuring at least one mold variable and connected to thedispensing apparatus and/or the operating system.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are only for purposes of illustrating certain embodimentsof, and are not to be construed as limiting, the invention.

FIG. 1 is a side view of a molding apparatus suitable for practicing themethod of the present invention.

FIG. 2 is a cross section through a vertical elevation of a mold cavity.

FIG. 3 is a top view of a molded substrate prior to being coated. Thesubstrate is shown having an area of increased thickness to promoteand/or channel flow of coating composition;

FIG. 4 and FIG. 5 are, respectively, front and back views of thesubstrate shown in FIG. 3.

FIG. 6 is a side view of a molded door panel. The door panel is providedwith areas of varying depth to channel flow of coating composition.

FIG. 7 is the substrate of FIG. 4 coated on a show surface thereof.

FIG. 8 is the substrate of FIG. 4 having a coating located substantiallyonly in a runner section of the show surface.

FIG. 9 is a front elevation view of a molded plaque with a substantiallyflat show surface.

FIG. 10 is a front view of a molded substrate with areas of varyingthickness illustrated.

FIG. 11 is a plan view of a substrate having a removable, flexiblecontainment flange.

FIG. 12 is a cross section of FIG. 11 through 12-12 illustrating aremovable flange.

FIGS. 13A through 13D are cross sectional illustrations of moldedsubstrates having removable flanges of various configurations.

FIG. 14 is a plan view of a substrate having a removable flangeextending around the perimeter of the substrate show surface.

FIG. 15A is a plan view of a substrate having a removable flange on theshow surface of as well as on the perimeter so as to contain the coatingto a predetermined area of the show surface, while FIG. 15B is a crosssectional view of a FIG. 15A through 15B-15B.

FIG. 16 is a cross section of a stationary mold half of the type shownin FIG. 1.

FIG. 17A is a front view of a molded substrate containing a readilycompressible area at the location where a coating composition is to beinjected onto the surface of the substrate, while FIG. 17B is across-sectional side view of FIG. 17A through lines 17B-17B andillustrates a compressible area below the point of coating compositioninjection, and FIG. 17C is a front view of the molded substrate of FIG.17A wherein the substrate has been coated.

FIG. 18A is a front view of a molded substrate containing a readilycompressible area at the location wherein a coating composition is to beinjected onto the surface of the substrate; FIG. 18B is across-sectional side view of the plaque shown in FIG. 18A while themolded substrate is still in a mold cavity and a coating composition hasbeen applied to the show surface of the substrate, and FIG. 18C is thefront view of the coated article shown in FIG. 18B.

FIG. 19 is a partial schematic view of a molding apparatus capable ofcoating a molded substrate and incorporating a mold runner.

FIG. 20 is a schematic view of a mold cavity having a mold runner and aninlet for introduction of an IMC composition.

FIG. 21 is a schematic view of the mold cavity from in FIG. 20 where themold cavity has been filled with a substrate-forming composition and anIMC has been applied thereto. The mold runner having a containmentshroud prevents coating composition from entering the injector for thesubstrate-forming material.

FIG. 22 is a schematic view of a mold runner in a mold half while FIG.22( a) is a close up view of the containment shroud illustrated in FIG.22.

FIGS. 23 and 24 are schematic views of other mold runners withcontainment shrouds.

FIG. 25 is a cross section through a mold half at a vertical sectionwhere a mold runner containment shroud is present.

FIG. 26 is a partial elevational view of a mold half having a barrieraround a gate pin apparatus for preventing an IMC composition fromentering a substrate injection device through the gate pin.

FIG. 27 is a partial elevational view of a coated substrate having abarrier which prevents IMC composition from entering the orifice of theinjector for the substrate-forming material.

FIGS. 28A through FIG. 28C are partial cross-sectional views through amold illustrating a gate pin and a barrier for coating composition flow.

FIG. 29 is a partial cross-sectional view through a mold illustrating acoated substrate having a barrier which prevents IMC composition fromentering the orifice of the injector for the substrate-forming material.

FIG. 30A through FIG. 30C are partial cross-sectional views through acoated substrate having barrier rims of varying configurations.

FIG. 31A through FIG. 31D are flow diagrams showing the flow of IMCcomposition over a “show” surface of a molded article.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In the drawings, like numerals indicate like or corresponding partsthroughout.

FIG. 1 shows a molding machine 10 which includes a first mold half 20that preferably remains in a stationary or fixed position relative to asecond moveable mold half 30. As can be appreciated, the method of thepresent invention can be practiced on a wide variety of mold types andstyles. Stationary mold half 20 is mounted to a platen 21 of moldingmachine 10. Moveable mold half 30 is mounted to platen 31 which ismounted to a clamping mechanism 70 of molding machine 10. FIG. 1 showsthe mold halves in an open position. Mold halves 20 and 30 can mate,thereby forming a mold cavity 40 therebetween as shown in at least FIG.2. Mold halves 20 and 30 mate along mold faces or surfaces 24 and 34,respectively, when the molding apparatus is in the closed position,forming a parting line 42.

Moveable mold half 30 reciprocates generally along a horizontal axisrelative to the first or fixed mold half 20 by action of clampingmechanism 70 with a clamp actuator 72 such as through a hydraulic,mechanical, or electrical actuator as known in the art. The clampingpressure exerted by clamping mechanism 70 preferably has an operatingpressure in excess of the pressures generated or exerted by the firstcomposition injector and the coating composition injector. For example,pressure exerted by clamping mechanism 70 can range generally from 15 to100 MPa (˜2000 to ˜15,000 psi), preferably from 27.5 to 85 MPa (˜4000 to˜12,000 psi), and more preferably from 40 to 70 MPa (˜6000 to ˜10,000psi) of the mold surface.

In FIG. 2, mold halves 20 and 30 are shown in a closed position, abuttedor mated along parting line 42. As illustrated, mold cavity 40 is shownin cross section, although the design of the cavity can vary greatly insize and shape according to the end product to be molded. Mold cavity 40generally has a first surface 44 on first mold half 20, upon which ashow surface of an article will be formed, and a corresponding back sideor opposite second surface 46 on second mold half 30. Mold cavity 40 ismodified to contain separate orifices to allow the substrate-formingcomposition and the coating composition to be injected independently.The location of the injectors and injection orifices can vary fromapparatus to apparatus, and from part to part, and can be based onfactors such as efficiency, functionality, workpiece geometry, etc.

As also shown in FIG. 1, the first (substrate-forming) compositioninjector 50 is a typical injection molding apparatus capable ofinjecting a thermoplastic or thermoset material, generally a moltenresin, into the mold cavity. First injector 50 is shown in a“backed-off” position, but the same can be moved to a horizontaldirection so that nozzle or resin outlet 58 mates with mold half 20 andcan inject into mold cavity 40.

For purposes of illustration, first injector 50 is shown as areciprocating-screw machine wherein a first composition is placed inhopper 52 and rotating screw 56 moves the composition through heatedextruder barrel 54, where it is heated above its melting point. Asheated material collects near the end of barrel 54, screw 56 acts as aninjection ram and forces the material through nozzle 58 and into moldcavity 40. Nozzle 58 generally has a non-return valve at the nozzle orscrew tip to prevent the back flow of material into screw 56.

Because of the size and/or complexity of the part being formed,extrudate sometimes may be injected into the mold from more than onelocation. To control the flow of the extrudate through a manifold, itmay be necessary to heat the extrudate. These manifold passages may bereferred to as hot runners or manifold systems and are shown in detailin FIG. 16.

In operation, a predetermined quantity of a substrate-forming materialis injected into mold cavity 40 from first injector 50, forming asubstrate or workpiece. Substrate formed in the mold cavity has at leasta show surface 82 and an opposite surface 84.

Suitable thermoplastic substrates include but are not limited to nylon,polyethylene terephthalate (PET), acrylonitrile-butadiene-styrene (ABS)resin, acrylic, polystyrene, acetal, polycarbonate, polyolefins such aspolyethylene and polyethylene, polypropylene, and polyvinyl chloride(PVC). This list is not exhaustive, only illustrative.

The present method involves the design and manufacture of a mold whichallows an IMC composition to be introduced into mold cavity 40 from asecond injector 60. Injection of IMC composition begins after thesubstrate-forming material has developed sufficient modulus to receive acoating or when the mold cavity pressure or temperature is within adesired range. These conditions are described in more detail below.

In FIG. 2, second injector 60 is connected to a second nozzle 62 whichis located in the mold half not containing the first injector 50. Morespecifically, first composition injection 50 is shown as located infixed mold half 20 and second composition injector 60 is located inmovable mold half 30. However, the position or number of second nozzle62 is based on the portion of the workpiece to be coated and itsgeometry.

As shown in FIG. 2, the IMC composition 90 is injected through secondnozzle 62 into mold cavity 40. The mold is not opened or unclampedbefore the IMC is applied. That is, the mold halves maintain a partingline and remain in a closed position during the injection of bothcompositions. IMC composition 90 spreads out and coats a predeterminedportion or area of show surface 82.

FIG. 16 depicts a hypothetical first or stationary mold half of thegeneral design shown in FIG. 1. The drawing depicts a typical runnersystem inside the mold used for the delivery of the substrate-formingmaterial into the mold cavity and is illustrative of two types of gates,namely hot tip as indicated by 160 and valve gate system as indicated by170. In FIG. 16, 100 is a mold half. The polymer being fabricated isdelivered from the injection unit through the bushing 112. Cavity plate110 is the portion of the mold adjacent the part to be formed. A nozzletip insulator 114 prevents the cavity plate from acting as a heat sink.Nozzle heater 115 is also part of the system to maintain the correcttemperature of the molten material being injected.

The manifold heater 118 functions to keep manifold 140 hot. Sprueinsulator 120 functions as part of the temperature maintenance system.Nozzle tip 122 is the actual point of delivery into the mold of themolten material and is located in nozzle housing 124. Lines throughwhich water or oil are circulated to heat or cool, as is required by thepolymer being used, are indicated by 126 and 128. Manifold heater 130,nozzle insulator 132 and air gap 134 all are part of the temperaturemaintenance system. Locating ring 136 is used to locate the moldrelative to the injection nozzle. Sprue heater 138 is located on spruebushing 142. Valve gate 144 is part of the delivery system for nozzletip 122 and is actuated by air open conduit 150 and air close conduit148. Pressure transducer 180 measures the pressure in the mold; morethan one such transducer generally is used. A temperature transducer 182is used to determine the temperature in the mold; more than one suchtransducer generally is used.

Injection of the material used to form the substrate can be viewed as athree-stage process. The first stage is usually referred to as injectionhigh. The optimum pressure used to inject the material from theinjection machine into the mold can be determined by experimentation,but it preferably is sufficiently great so that the mold is filled to atleast about 85 to 95% of its capacity. The pressure time, plastic moldsize, and configuration are all determining factors. Generally, thepressure is increased until flash is noticed at the parting line of themold, at which point pressure is slightly decreased.

The second stage of injection is referred to as injection pack. It toocan be determined by a series of experiments and preferably is of amagnitude such that, at its completion, the mold cavity is filled to atleast 99% of its capacity.

After injection pack, injection pressure is reduced to keep theworkpiece from distorting. This begins the third stage, referred to asinjection hold. As with the others, it can be determined byexperimentation.

In designing a mold, determining the ultimate machine conditions of thesystem in connection with a specific mold, a specific substrate materialand a specific IMC composition can be important. In setting up a mold, alarge number of variables must be interrelated to produce acceptableparts in a commercially acceptable amount of time. Pressures, times andother settings of the injection machine vary with the shape of the partbeing manufactured and/or the polymeric material being used.

To optimize these and the other critical operating parameters of theinjection process, a flow modeling analysis based on the desired articleshape can be performed and/or a series of experiments can be run on anexisting mold (if it exists) or a mock-up. In addition, flow modelingand/or experimental runs can be performed on the new mold design toevaluate performance and determine if modifications are needed beforethe mold is put into production With respect to the variables, thevolume of a given mold may be calculated. Based on this calculation andthe density of the substrate-forming material, charge size can bedetermined. Differing machine variables can be tried until an optimum,complete filling of the mold in a minimum time, is determined.Preferably in these experiments, the mold is fitted with one or moretransducers and/or sensors which measure pressure and/or temperaturewhile various machine variables (e.g., injection speeds and pressures)are altered. Flow modeling based on the mold to optimize the operatingparameters also can be performed.

Variations in the amount of resin injected are tolerable in an amount of±0.5% of the total weight of the charge. Such variations occur in partbecause the resin is compressible and acceptable parts are producedwithin this range.

Determining optimum operating variables in the injection molding of anew part basically is an iterative (i.e., trial-and-error) technique.While an experienced technician may have some idea as to what isrequired, he nonetheless will generate a certain amount of scrap withany new configuration. Choices are made for certain variables such as,e.g., barrel temperature, mold temperature, injection high pressurelimit, injection hold pressure, injection speed, fill time, and holdingtime. Extreme adjustments are made in an effort to bracket operableconditions which then may be fine tuned, and this is referred to hereinas a bracketing procedure.

To exemplify this process, a series of experiments were run using amodified 771 Mg (850 ton) CINCINNATI MILACRON™ hydraulic clamp injectionmolding machine and a mold to determine the optimum machine settings inrespect of a number of substrate materials. The machine settings foundto yield optimum results are set out in Table I below. These settingswere arrived at using a bracketing procedure. The mold used in thisprocedure resembles a valve cover for an automobile engine essentiallyhaving the shape of an open box with turned down sides.

These results might not necessarily be applicable to another moldingmachine. Rather, a new series of tests might be necessary based on thesystem to be modified. This is also true in the case of a different moldor resin. In such a case, similar tests would need to be run to findoptimum operating parameters.

The following resins were used as the substrate-forming material:

EXAMPLE 1 IMPET™ EKX215 Glass-filled Polyester (Ticona; Summit, N.J.)EXAMPLE 2 IMPET™ EKX230 Glass-filled Polyester (Ticona) EXAMPLE 3FORTRON™ 4184L6 Polyphenylene Sulfide (Ticona) EXAMPLE 4 FORTRON™ 1140L7Polyphenylene Sulfide (Ticona) EXAMPLE 4 XENOY™ 2390 PC/PBT Alloy (GEPlastics; Pittsfield, Mass.) EXAMPLE 5 NNP-30-2000 Polystyrene (NovaChemicals Corp.; Calgary, Alberta).

TABLE I Molding of Various Thermoplastics Example 1 Example 2 Example 3Machine set-points Nozzle (° C.) 261 261 304 Barrel temp., zones 265,266, 265, 266, 314, 309, A-D (° C.) 266, 265  266, 265  308, 303  Moldtemp., zones 260, 260, 260, 260, 304, 304, 1-8 (° C.) 149, 260, 149,260, 149, 304, 149, 260, 149, 260, 149, 304, 260, 260 260, 260  304,316  Stationary mold 117 117 133 temp. (° C.) Moving mold temp. 135 135147 (° C.) Inj. High, Pack, 10.0, 4.0, 10.0, 4.0, 10.0, 3.0, Hold (sec)4.0 4.0 2.0 Cooling (sec) 90.0 60.0 60.0 Clamp open (sec) 0.0 0.0 0.0Ejector forward 0.99 0.0 0.0 dwell (sec) Extruder delay 0.0 0.0 0.0(sec) Core Set (Sec) 0.8 0.8 0.8 Inj. high pressure 15.2 15.2 15.2 limit(MPa) Inj. Pack pressure 6.9, 6.9 7.6, 7.6 5.5, 5.5 1, 2 (MPa) Inj. Holdpressure 6.2, 6.2 6.2, 6.2 4.8, 4.8 1, 2 (MPa) Shot size (cm) 7.87 7.756.86 Transfer position 3.56 1.78 3.05 (cm) Decompression 0, 0.76 0, 0.760, 0.76 before, after (cm) Inj. speed, % of shot size Seq. 1 1.25, 801.25, 80 1.00, 80 Seq. 2 1.10, 60 1.10, 60 1.00, 60 Seq. 3 1.00, 401.00, 40 1.00, 40 Seq. 4 1.00, 20 0.60, 20 1.00, 20 Seq. 5 0.60, X-FER0.60, X-FER 0.60, X-FER Example 4 Example 5 Example 6 Machine set-pointsNozzle (° C.) 304 288 272 Barrel temp., zones 314, 309, 288, 288, 282,282, A-D (° C.) 308, 303  288, 288  276, 272  Mold temp., zones 304,304, 288, 288, - n/a - 1-8 (° C.) 149, 304, n/a, 149, 304, 288, 288,304, 316  n/a, 288, 288  Stationary mold 133 109 86 temp. (° C.) Movingmold temp. 147 141 119 (° C.) Inj. High, Pack, 10.0, 3.0, 10.0, 3.0,8.0, 2.0, Hold (sec) 2.0 2.0 2.0 Cooling (sec) 60.0 120.0 140.0 Clampopen (sec) 0.0 0.0 0.0 Ejector forward 0.0 0.0 0.0 dwell (sec) Extruderdelay 0.0 0.0 0.0 (sec) Core Set (Sec) 0.8 0.8 0.8 Inj. high pressure15.2 15.2 15.2 limit (MPa) Inj. Pack pressure 5.5, 5.5 8.3, 8.3 9.7, 9.71, 2 (MPa) Inj. Hold pressure 4.8, 4.8 7.2, 7.2 8.3, 8.3 1, 2 (MPa) Shotsize (cm) 6.86 7.87 8.38 Transfer position 3.05 2.03 2.03 (cm)Decompression 0.00, 0.76 0.00, 0.76 0.00, 0.56 before, after (cm) Inj.speed, % of shot size Seq. 1 1.00 80 2.25, 80 2.75, 80 Seq. 2 1.00 602.50, 60 2.50, 60 Seq. 3 1.00 40 2.25, 40 2.25, 40 Seq. 4 1.00 20 0.40,20 2.00, 20 Seq. 5 0.60 80 0.60, X-FER 1.00, X-FER n/a = not applicable

Having determined the operating parameters for production of thesubstrate, one then determines, by reference to appropriate tables or bymeasurement, the melt temperature of the substrate-forming material sothat the IMC composition may be injected at the proper time. By use oftransducers or sensors referred to above with respect to FIG. 16, it ispossible to determine when the temperature of the substrate has cooledbelow the melt temperature of its constituent material(s).Alternatively, the melt temperature can be determined indirectly byobserving pressure. When a molded part reaches its melt temperature, itstarts to contract somewhat, thus reducing the pressure.

If transducers are not used, the time when the melt temperature isreached and injection of IMC composition commences can be determined andthen used to control the operation. In other words, the length of timebetween the mold closing and the substrate reaching its melt temperaturecan be determined and used to control the start of injection of IMCcomposition.

A series of experiments using a modified machine and IMPET™ 430 resinand STYLECOAT™ X primer (OMNOVA Solutions Inc.; Fairlawn, Ohio) as theIMC composition were run. By temperature measurements, the substrateresin was determined to have cooled sufficiently below its melt point 50seconds after the mold had closed. Three parts were run using a90-second cure time for the IMC. These parts showed good coverage andcuring.

A further 33 parts were run to confirm these machine settings and all ofthe parts were acceptable, i.e., good appearance and adhesion. A furthersample was run injecting the IMC only 30 seconds after the mold closedand using a cure time of only 60 seconds. This part was unacceptablebecause some portions were only lightly coated. This confirmed thecorrectness of previous machine settings.

Another series of parts were made using VANDAR™ 9114 PBT polyester alloyas a substrate resin. The resin had cooled below its melt temperature 30seconds after the mold closed. These parts all demonstrated goodappearance, i.e., even coverage and good adhesion.

To illustrate more clearly the necessity of injecting the IMCcomposition at the proper time (i.e., immediately after the surface ofthe substrate resin cools to its melt temperature) contrasted with aninjection that occurs too early or too late, a series of experiments (5parts each) was run on a modified TOSHIBA™ 950 injection molding machineusing a hydraulic clamp, VANDAR™ 700 resin, and STYLECOAT™ primer as IMCcomposition. The machine settings were determined as described above andwere identical except for the time at which the IMC composition wasinjected, i.e., the interval in seconds between the closing of the moldand the commencement of the injection of the IMC. The results of theseexperiments are set forth in Table II below.

TABLE II Cure Interval time Coater Coater Appear- (sec.) (sec.) settingspeed ance Comment 10 160 235 slow poor Coating intermingled withsubstrate 15 160 235 slow poor Coating intermingled with substrate 25160 235 slow poor Coating intermingled with substrate 40 160 225 slowgood Extended cure time for center of parts to have good cure 100 160235 slow poor Coating not well adhered and poor coverage 120 160 235slow poor Coating not well adhered and poor coverage

These examples demonstrate the desirability of determining and settingthe system so that the IMC composition is injected at the time when thesurface temperature of the substrate just falls below its melttemperature. Thus, the present method can include determining andsetting the operating parameters including optimal time to inject theIMC composition.

As stated above, a substrate can be selectively coated in predeterminedareas. In addition, the selective coating can be further controlled bydesigning the mold to control or modify the thickness or depth of thesubstrate. In this respect, the thickness or depth is defined as adistance, girth, or dimension from one surface to the opposite surfaceof the substrate. The modification to the mold for increasing the IMCcomposition flow is generally concerned with the depth between twosurfaces, the first being a surface to which an IMC composition isselectively directed or applied, commonly referred to as a show orappearance surface, and the back surface that is substantially opposite.The IMC may but does not necessarily cover the entire show surface. Forexample in FIG. 3 thickness refers to the distance from show surface 82to the backside or opposite surface 84. As shown in FIG. 3, thethickness between the show surface and back side of the substrate canvary.

Each substrate inherently has a compressibility factor, i.e., at a giventemperature, a given substrate is compressible to a specific, calculablepercentage. Therefore, even though a molded article or substrate has asingle compressibility ratio, a first area of a substrate which isthicker than a second area can compress a greater thickness or distance.For example, a given substrate might have a compressibility ratio of 20%at a certain temperature. Therefore, a portion of that substrate whichhas a thickness of 2.0 cm can compress 0.4 cm whereas another portionwhich has a thickness of 1.0 cm can only compress 0.2 cm at the sametemperature.

This compressibility can be utilized to selectively coat predeterminedareas of a substrate by modifying the mold accordingly. Substratecompressibility also can be utilized to effectively direct the flow ofan IMC into certain areas or pathways of a substrate.

As stated above, IMCs can be applied to a substrate in numerous, wellknown ways. Referring to FIG. 2, shown is an IMC (or second) compositioninjector 60 having a nozzle 62 on the molding apparatus in a suitablelocation such as on mold half 30. A first quantity of the firstcomposition is injected into a mold cavity to a desired predeterminedlevel, forming a substrate, work piece, or article, such as plaque 100shown in the views of FIGS. 3-5.

As shown in FIG. 3, the substrate has at least a show surface 82 andback side 84. An IMC composition 90 is then injected into the moldcavity from injector 60 through at least one nozzle 62 onto the showsurface side of the substrate at a location such as 104 on tab 103 asshown in FIG. 4.

The mold is not opened or unclamped before and/or during injection andcuring of the IMC composition, that is, the mold halves maintain aparting line and generally remain a substantially fixed distance fromeach other while both the first and second compositions are injectedinto the mold cavity.

The liquid IMC composition disperses or radiates onto show surface 82from the point of injection 104, the location of which depends on wherethe IMC composition injector and nozzle thereof is positioned in themodified molding apparatus. Accordingly, the point where the IMCcomposition is injected can be substantially anywhere on show surface 82and is not limited to the locations shown in the drawings.

The IMC composition cures on the substrate so as to form a coating. Thecure is optionally heat activated from sources including, but notlimited to, the molded substrate, the mold itself, or by temperaturecontrolled fluid flowing through the mold.

Modification of the mold can include directing or channeling the flow ofan IMC composition on the substrate. As stated above, through thecontrol of variables of the molding process, an amount of material thatwill produce a desired substrate can be determined experimentally or byflow modeling. After the first composition has been injected into themold cavity and has cooled below the melt point or otherwise reached atemperature sufficient to accept or support an IMC, a predeterminedamount of IMC composition is injected from injector 60 onto an injectionpoint of the substrate, preferably on a show surface thereof. Thecoating composition is injected at a pressure that ranges generally fromabout 3.5 to about 35 MPa (500 to 5000 psi) and typically from about 7to about 30 MPa (1000 to 4500 psi) so as to promote the spread of theIMC composition away from the nozzle between a mold surface and asurface of the substrate. Flow of the IMC is controlled by modifying themold to vary the thickness or depth of the resin of the substrate belowthe surface to be coated which directs the IMC to preferred areas of thesubstrate. For example, if a mold cavity is designed so that a substratehas a constant thickness under an area to be coated, the IMC compositionwill spread from the location of injection in a substantially radial,even, constant manner. Under the same relative conditions, if asubstrate is formed having areas which vary in thickness under thesurface area to be coated, the IMC composition can be channeled to flowin area(s) of greater relative thickness. Thus, the depth of the coatingalso can vary on the coated surface. The compressibility of thesubstrate allows a substrate area having a greater depth relation to asecond area to compress more and better accommodate IMC flow and promotemigration thereof. Substrate temperature also is a factor incompressibility and, therefore, a factor affecting flow.

In another potential mold design, a substrate is provided with an areaof increased thickness around the point where the IMC composition isinjected onto the substrate. By increased thickness is meant that thethickness of the substrate around the IMC composition injection locationis greater than the thickness of at least one other area or section ofthe substrate. As shown in FIG. 5, plaque 100 is shown with a tab area103 at a location of IMC injection. The thickness of tab area 103 can bevaried to enhance channeling of the IMC composition. Tab section 104 inFIG. 4 includes a thin section or containment tab flange 102 whichprevents the IMC composition from flowing out of the mold cavity. Thecontainment flange will be further discussed below. The relatively thicktab area promotes coating composition flow from the IMC nozzle onto showsurface 82 of the substrate as the IMC composition tends to avoidsubstrate sections of minimal or lesser thickness such as the tab.

In yet a further option, a substrate is provided with at least one“runner” section, preferential flow channel, or area to promote IMCcomposition flow on a substrate. A runner is an area which is relativelythicker than another area adjacent thereto, wherein the IMC compositioncan be routed to flow preferentially. Advantageously, runner sectionscan be provided on substrates of complex design or otherwise difficultto coat. A runner section generally is located in an area on thesubstrate beginning near the point of injection of the IMC compositionand extending away therefrom to a predetermined point or terminus on thesubstrate. For example, FIG. 5 has a runner section 106 extending fromand including tab area 103 to substantially the bottom end 107 of plaque100; FIG. 6 shows a door panel having three runner sections 109.Depending on the amount of IMC composition injected into a mold cavity,the show surface having a runner section can be completely coated orcoated only in certain areas such as the runner section. The amount ofcoating applied and thickness thereof can vary from part to part.

The depth of the runner section can vary depending on the substrate tobe coated and design specifications. A substrate can have a runnersection extending from an area of IMC composition Injection which is sorelatively thick that all of the IMC application to the substratesurface remains substantially in the runner section. Therefore, as canbe imagined, many unique effects can be created by modifying the moldingsystem to utilize runner sections. For example, a runner section can beutilized to channel coating composition to a distal part of a substratesurface. The runner section thickness can be gradually decreased in adirection away from the point of injection as needed, or even separatedor divided into more than one runner section, to accomplish a desiredcoating effect.

A molded substrate or article also can be provided with a containmentflange 98. As shown in at least FIG. 4, containment flange 98 can extendcompletely around the perimeter of a substrate, specifically plaque 100.Flange 98 can be used as a barrier to prevent the IMC composition fromleaking out of the mold cavity and potentially blowing out of theparting line. As shown in at least FIG. 3, flange 98 is generally offsetor formed in a plane below that of show surface 82. Thus, show surface82 has an edge 83 which transitions into flange 98. Show surface edge 83drops off into a wall at an angle of about 90° relative to the showsurface. Substrate wall 86 terminates at flange portion 98, whereinflange portion extends at an angle of about 90° in relation to wall 86.The relatively sharp angles between show surface 82 and flange 98 aswell as the relative incompressibility of the thin flange act arebelieved to act as a substantial barrier to flow of IMC composition.Flange 98 generally has a thickness less than the thinnest portion orarea of the substrate. As shown in FIG. 3, flange 98 is thinner thansection 96, the relatively thinnest section of the substrate. Flange 98encompasses substantially the entire perimeter of a substrate surface tobe coated and generally has a width of no more than about 0.57 to about0.45 cm (0.225 to 0.176 in.), desirably no more than about 0.44 to about0.19 cm (0.175 to about 0.076 in.), and preferably no more than about0.19 to about 0.11 cm (0.075 to about 0.045 in.).

As shown in FIG. 7, IMC 90 covers the entire show surface of the moldedsubstrate. Due to the configuration of the molded substrate as well asother molding variables, coating 90 does not cover flange 98, althoughit can. Due to the design of flange 98, generally less than about 10%,desirably less than 5%, and preferably less than 1% by weight of the IMCcovers flange 98. Flange 98 is free of any other substrate material onthe distal edge thereof. There is no other substrate material or outeredge between the flange and the parting line.

The mold can also be modified to include a breakable, removable flashedge or containment flange. Molded articles, parts, or substrates mostoften are constructed to conform to certain predetermined, definitetolerances. Frequently, the articles are designed to fit exactly orsubstantially exactly into an assembly or working arrangement of parts.Articles provided with an additional containment flange to contain acoating often are larger than specified manufacturing tolerances.Furthermore, often the containment flange show surface is not coatedwith an IMC, leaving the article with an undesirable appearance.

Keeping a liquid, uncured IMC composition confined to an intendedsubstrate target surface area is extremely difficult. Frequently, thecomposition flows or leaks onto surrounding mold surfaces, such asaround the parting line; non-show surfaces of the article which are notto be coated; and even out of the mold itself. Another problemassociated with coating leakage is that the coating composition may notbecome properly packed in the mold resulting in coated parts having dullappearances, parts not having an even film build or adequate coatingthickness, or parts not exhibiting the desired or required texture.Coating seepage onto ejector pins can cause binding and inoperability ofthe molding apparatus. Such overflow is unacceptable as parts can beruined, and mold surfaces must be cleaned to remove coating buildup.

A mold designed according to the present method prevents theaforementioned problems by incorporating into the molded article orworkpiece an IMC containment flange or flash edge which is flexible andthus easily removable, e.g., by hand after the article has been coatedand the coating cured. The coated article with the removable containmentedge removed can be used as-is in an assembly. One advantage of theremovable containment flange, which may only be partly coated andpossibly unsightly, is that it can be easily removed and discarded.Moreover, a fully coated part of desired dimensions and exact standardscan be produced. Labor and monetary savings are other advantages ascoating containment is achieved, and waste is minimized. The removablecontainment flange potentially eliminates part painting operations,secondary handling, and shipping costs between a part molder and apainter.

Referring to FIGS. 11-15B, molded articles or substrates havingremovable flexible containment flanges are shown. Shown in FIG. 11 is anarticle 200. The main or show surface 210 is coated. Due to the presenceof the removable containment flange 220, the IMC composition isprevented from leaving the surface of the substrate and contaminatingother mold surfaces or the back side of the molded article.

FIG. 11 also illustrates substrate injection area 230 where thesubstrate-forming material was injected into the mold. IMC compositioninjection area 240 shows the ingress point of the IMC composition whichthen has spread across the show surface. Removable flange 220 extendsaround the periphery of the show surface to inhibit flow off of the mainsurface, excepting the area around the injection area 240 which alreadyincludes a feature for containment. Removable flange 220 is shown asextending around the entire periphery of the show surface, although itcould extend around only a portion if, e.g., the workpiece includes flowrestricting geometry. FIG. 14 shows a removable flange 220 extendingaround the periphery of the main surface of substrate 200. IMCcomposition injection inlet area 240 is also shown. Again, the removableflange can extend less than the complete distance around the perimeterof the substrate main portion if some other containment feature ispresent or substantially no leakage occurs in the specific area.

The removable flange is located or formed on a substrate surface in anarea or plane between the show surface edge or perimeter and a backsideedge or perimeter of the part. No matter which flange is utilized, eachflange has a width and a depth or height. As shown in FIG. 12, the widthA can be defined as the greatest distance the flange extends outward oraway from the substrate main body C at a location between a show surfaceD to be coated and the non-show surface E opposite therefrom. Depth Bcan be considered a depth or thickness measurement, which can vary alongthe width of the flange, with the greatest depth generally existing atthe outermost portion of the flange. The flange is designed to have avery thin section located adjacent to, or in the vicinity of, thesubstrate which is readily breakable. Removing the flange is as simpleas, for example, flexing it back and forth to break the leading edgethereof away from the edge of the part main surface. Although notnecessary, the flange also can be removed with tools such as a cuttingedge, hot edge tools, water jet, buffer, sander, router, and the like.

The removable flange can have numerous configurations. FIG. 12 shows across section through FIG. 11 wherein the flange 220 is formed as awedge having a depth greater at its outer end portion than where thesame contacts and removably connects to the substrate main body. Theremovable containment flange can be formed only on one side of theparting line 205. The angle between the vertical side surface of thesubstrate main body and containment flange top surface can vary fromabout 10 to about 90° and is preferably from about 15 to about 30°. FIG.13A shows a cross section of a coated substrate 220 with IMC 216 onsubstrate 215 and triangular flange 221. A rectangular flange 222 isshown in the configuration of FIG. 13B. Circular and semicircularflanges can also be utilized as shown in FIGS. 13C and 13D respectively.The flange can be almost any geometric shape or design such as anellipse, teardrop, or taper, etc.

For the flange to be easily removable, its point of attachment should besufficiently thin to be easily separated or broken away from thesubstrate main portion. The thickness of the flange depends on thesubstrate-forming composition. Accordingly, the thickness of the flangeat the point of attachment immediately adjacent to the substrate is lessthan about 0.7, 0.6 or 0.5 mm, and preferably is from about 0.1 to about0.4 mm. The thickness of the flange in a direction away from the pointof attachment to the substrate main portion can increase to anydesirable thickness, which Is generally greater than the thickness atthe point of attachment. The width of the flange from the substrate mainportion to the peripheral edge thereof is generally less than about 10mm, desirably from about 2.5 to about 8 mm, and preferably from about 3to about 6 mm.

The mold can be modified so that the removable containment flange isformed into either or both of the mold halves described above as bymachining, milling operation, or the like. The flange typically isformed along one or both sides of parting line 205 as shown in, e.g.,FIG. 12. Due to the design and substantial incompressibility of thecontainment flange at the narrow point of attachment to the substratemain portion, the IMC composition predominately stops at the attachmentpoint between the substrate main body and containment flange as shown inFIGS. 13A-D. That is, a compression gradient is formed and the IMC isable to flow across the relatively thick, compressible substrate mainportion but cannot substantially flow across the relatively thinincompressible containment flange edge attached to the substrate mainportion.

The mold can be designed so that the removable containment flangeextends onto a surface of a substrate to prevent flow of IMC compositiononto predetermined areas of the show or other surface. FIG. 15Aillustrates a substrate 300 having a removable containment flange 320extending across a portion of show surface D as well as around a portionof the perimeter of the substrate to contain IMC 316 to a predeterminedarea of show surface D.

FIG. 15B is a cross sectional view through 15B-15B of FIG. 15A. Thisview shows that IMC 316 is contained in a predetermined portion of showsurface D by removable flange 320.

Accordingly, the removable IMC containment flange can be utilized in anyarea(s) on any surface of a substrate to preferentially coatpredetermined portions thereof. Crisply defined coating boundaries orareas on a substrate can be created when a removable containment flangeis utilized on a substrate, especially a show surface thereof. Manydifferent surface aesthetic effects can be created utilizing containmentflanges, especially removable ones. Obviously, the modification to themold can include any number of containment flanges. The containmentflange can be utilized to create any type of pattern, design, logo,lettering, insignia, etc. Different colored coatings can be incorporatedon different areas of a substrate which have containment flangeboundaries, thus allowing for shading, contrasting colors, specialeffects, etc.

Removable containment flanges also can be used on a substrate at an edgeopening adjacent to a moveable mold section such as a slide or core. Theremovable flange will prevent or block IMC composition from leaking intothe moveable core area and possibly binding the same.

Referring to FIGS. 17A-18C, shown is yet another mold modification. Inthis respect, IMC composition can be injected on a center portion of asubstrate surface at 310 of substrate 325 as shown in FIG. 17A, or acorner of a substrate surface at 410 of substrate 400 as shown in FIG.18A. Typically, the IMC composition is injected at a location on amolded substrate that is inconspicuous when the article is used.Alternatively, the IMC composition can be injected onto a portion of thesubstrate that later can be removed or cut away from the substrate. Forexample, if desired, the IMC composition injection area at tab 103 ofFIG. 4 can be cut away where it connects to the main portion of themolded substrate, leaving a substantially square coated article.

As stated above, IMC composition flow can be promoted or enhanced bycreating an area of increased relative thickness or a compressible zoneon the substrate at the location of IMC injection. FIGS. 17A-Cillustrate a molded substrate 325 including a compression differentialto promote flow on a substrate. FIG. 17A is a front view of substrate325 wherein a containment flange 330 can be utilized to confine the IMCto the show surface 302 of the substrate. The IMC composition can beinjected onto the injection inlet area 310 of the substrate during amolding cycle. Area of substrate injection 312 is also illustrated inphantom as the substrate has been injected from the back side 304opposite of show surface 302 to hide any flow lines or undesirable edgeswhich may be present after a sprue is removed.

The area of increased thickness 308 forms a “flow zone” which isselectively used to control the flow of the coating composition and thusthe thickness and surface area of the resultant coating. For example,for an area of increased relative thickness that has a correspondingincreased compressibility, the flow zone promotes flow of the IMCcomposition to the contiguous surface of the substrate for the areaadjacent thereto which has a relatively thinner cross section. This flowzone is also adjacent the injection site for the coating and is distinctfrom other complex cross sections having increased thickness as mayoccur from reinforcing struts or similar structural details insofar asthe flow zone is designed for selectively controlling the flow of thecoating by providing a channel of increased (or decreased)compressibility. These areas of increased (or decreased) thickness mayalso serve as flow zones, however. Likewise, the flow zone may comprisean area of decreased compressibility such as occurs for a thinner crosssection area like a peripheral flange. In this case, the flow zone actsas containment zone for the coating and does not need to be adjacent to,and in fact probably will be remote from, the injection site.

FIG. 17B shows a cross-sectional side view through 17B-17B of the moldedsubstrate of FIG. 17A. Show surface 302 and back surface 304 have avariable distance or thickness there-between. Sprue 314 is formed duringthe substrate injection molding step. The area behind injection inletarea 310 is provided with area 308 that has a greater thickness thansubstrate regions 306 to promote IMC composition flow. Area 308 has athicker section or greatest depth at its central portion where the IMCcomposition is injected onto show surface 302. The thickness of thesubstrate tapers from injection inlet area 310 and reaches a relativelyconstant depth in substrate section 306. The relative depth or thicknessprovided by area 308 provides a readily compressible area for the IMCcomposition and promotes flow to other desired areas of show surface302. As shown in FIG. 17C, IMC 320 completely covers show surface 302.Alternatively, if desired, substrate 325 can contain other compressiondifferential zones such as a mold runner described above and can becoated in pre-selected areas utilizing substrate compressibility.

FIGS. 18A-C show another use of substrate compressibility to create acompression differential which promotes IMC composition flow at aninjection inlet area. FIG. 18A shows substrate 400 with show surface 402and containment flange 430. IMC composition is injected at inlet area410. Substrate-forming material is injected at a location behind area412. FIG. 18B is a partial cross section of plaque 400 situated in amold cavity 440 between mold halves 442 and 444. The molded substratehas been coated with IMC composition 420 from injection device 422through inlet channel 424 via a nozzle at inlet area 410. The moldparting line 460 also is illustrated. The IMC composition is injectedonto the substrate at area 408 which has an increased thickness comparedto other portions of the substrate including area 406. The IMCcomposition can more easily compress the substrate in area 408 ascompared to area 406 due to the increased thickness thereof. FIG. 18Cillustrates the front view of show surface 401 of coated substrate 400.

The substrate has a thickness ratio at the location of IMC injection(such as 310 in FIG. 17A) relative to another portion of the substrateintended to be coated of from about 1.1:1 to about 10:1, desirably fromabout 1.25:1 to about 2:1, and preferably from about 1.3:1 to about1.5:1.

To promote smooth, even flow of IMC composition across the show surface,a smooth or substantially constant transition is made from the locationof IMC composition injection to the other substrate areas as shown inFIGS. 17B and 18B. The transition zone can be considered as a taper orramp. Of course, as stated herein other features such as runner sectionsand coating containment flanges also can be incorporated to control orpromote IMC composition flow. In addition, controlling the substrateand/or mold temperatures can affect this flow.

FIGS. 19-25 show a mold runner 22. Referring to FIG. 20, firstcomposition injector 50 is shown contacting mold half 20 so that nozzleor resin outlet 58 mates with mold half 20 and can inject into moldcavity 40 through mold runner 22. Mold runner 22 provides a passagewayin the mold half for transferring a substrate composition from injector50 into mold cavity 40. The mold runner may also be referred to as asprue bushing, mold runner drop, etc.

FIG. 22 shows a schematic view of one type of mold runner 22 which has abody member that can be separate from or integral with a mold half 20 orplaten 21, i.e., the mold runner can be a separate, removable, anddistinct member inserted in and attached to a mold half or can be formedor shaped into a mold half itself. Mold runner 22 has a first and secondends, 23 and 25, and extends therebetween. First end 23 receives meltedmaterial from the injection molding machine and second end 25 dischargesthe material into the mold cavity 40, with the material subsequentlyforming a substrate in the mold cavity which can be coated. Mold runner22, except in the region of the containment shroud, is cylindrical incross section to avoid placing stress, strain, and shear forces on thesubstrate during injection; other suitable shapes, include but are notlimited to, conical, helical, and tapered, etc. As shown in at leastFIG. 20, the nozzle 58 is positioned or seated at first end 23 for amolding operation. Mold runner 22 includes containment shroud 27 whichprevents IMC composition from flowing or terminates such flow throughpassageway 26 and into the molding apparatus 50.

The containment shroud is generally a recess or void which extendsaround the entire perimeter or circumference of at least one portion ofthe mold runner passageway between the first and second ends. In otherwords, the containment shroud is generally a cavity, formed in the moldrunner about a peripheral segment of the passageway generally on a planesubstantially perpendicular to the passageway axis. Each containmentshroud has a base portion and a terminal or end portion as shown as 28and 29 respectively in at least FIG. 22( a). Base portion 28 has apredetermined width along an axial length of the passageway. Thecontainment shroud also has a height and extends generally radiallyoutward from the passageway perimeter.

As noted above, the containment shroud has a design or structureeffective to prevent or terminate an IMC composition from passingtherearound or therethrough from the passageway egress to the passagewaysubstrate-forming material entrance. After the substrate-formingcomposition has been injected into the mold cavity, the mold runner andcontainment shroud are also filled therewith. The filled shroud utilizesthe relative incompressibility of the substrate in this thin area as abarrier to prevent IMC composition flow.

In another example of a runner, the base portion has a width orthickness greater than or equal to the terminal portion, such as shownin FIGS. 23 and 24, to allow substantially easy removal of the partiallycoated substrate sprue including a projection formed in the containmentshroud. The width of the base portion can vary but generally ranges fromabout 0.025 to about 6.5 mm and preferably from about 0.06 to about 0.4mm. Accordingly, the terminal or radially outward portions of thecontainment shroud often have a width less than the base portion. Theheight of the containment shroud between the base portion and theterminal portion can vary but generally is from about 0.1 to about 2 mm,desirably from about 0.2 to about 0.65 mm, and preferably from about0.25 to about 0.4 mm. The containment shroud can be located anywherealong the mold runner passageway between first and second ends 23 and25, respectively. Preferably the containment shroud is located towardthe second end where the IMC composition can enter the mold runner. Thecontainment shroud can be located as close to the second end as about0.25 mm. The shroud design and location depends on numerous factors suchas the diameter of the runner, the substrate composition and the need toremove the molded workpiece from the mold.

In FIG. 22, the containment shroud 27A is shown as an annular ringhaving a plane perpendicular to the axis formed by the passagewaybetween first and second ends 23 and 25, respectively. The annular ringhas squared-off corners at the end portion thereof. FIG. 23 showscontainment shroud 27B which is set at an angle so that the sprue formedby the substrate which fills the passageway and containment shroud canbe easily removed from the mold runner after a molding and coatingoperation is performed and the coated part is removed from the mold.Shroud 27B is generally set at an angle Ø measured from an axis formedby the passageway and height measured from the base portion to theterminal portion. Angle Ø may vary from about 1° to about 90°, desirablyfrom about 25° to about 65°, and preferably from about 40° to about 55°.

The passageway in FIG. 23, between the containment shroud and second end25, is also shown to have a diameter greater than that of the passagewaybetween the containment shroud and first end 23. This configurationmakes the sprue easier to remove. Thus, when the sprue is pulled out ofthe mold in the direction of the mold cavity, the containment shroud isflexible and conforms to the diametrical space provided in thepassageway nearest the second end. The containment shroud also can havea taper or wedge 27C as shown in FIG. 24.

FIG. 25 illustrates a cross section through a vertical axis of a moldhalf at a location where the containment shroud is present such as inFIG. 22. As can be seen, containment shroud 27 extends completely aroundthe perimeter of passageway 26 to prevent IMC composition from flowingthrough the mold runner. The mold runner in this example is of acylindrical shape and therefore the containment shroud extends radiallyaround the passageway perimeter.

To understand how the mold runner functions, the following descriptionof an coating process is described, with reference made to FIGS. 19-25,a substrate-forming material is introduced into an injection moldingapparatus wherein the material is heated above its melting point. Thesubstrate-forming material is moved through the apparatus utilizingrotating screw 56 and deposited at the end of the barrel. During amolding cycle, the mold halves 20 and 30 are brought together in aclosed position as shown in FIG. 19 and the molten substrate-formingmaterial is injected from nozzle 58 of the injection molding apparatusthrough mold runner 22 into the mold cavity 40. Generally, an amount ofsubstrate material is injected into the mold cavity so that a finalproduct desirably fills the mold cavity. As shown in FIG. 19, thesubstrate-forming material takes the shape of the mold cavity and alsoincludes a sprue portion 53 which resides in mold runner 22, generallyconforming to the shape thereof and completely filling the same. Oncethe substrate-forming material has been injected, it begins to cool andsolidify until it reaches a point where an IMC composition can beapplied thereto. An IMC composition then is injected into mold cavity 40onto a show surface of the substrate material. As shown in FIG. 20,injector 60 injects an IMC composition onto show surface 44. Throughpressure, the IMC composition spreads from inlet 62 across show surface44. Inasmuch as the IMC is injected onto the same side of the substratematerial as sprue 53 and mold runner 22, the IMC composition will flowalong sprue 53 toward the injection apparatus 50.

FIG. 21 illustrates a coated substrate in a mold cavity wherein acontainment shroud has been utilized to prevent the IMC composition fromflowing through a mold runner. The uncured IMC composition spreads outacross the surface of the substrate and also enters second end 25 of themold runner 22. The coating composition travels up the sprue from thesecond end 25 toward the first end 23 of the mold runner due to thecompressibility of the sprue material. Once the IMC compositionencounters the containment shroud 27, it is prevented from any furtherspreading due to the relative incompressibility of the substratecomposition in the containment shroud. Thus, the IMC composition isprevented from reaching first end 23 and entering injection apparatus 50and contaminating the substrate-forming material therein.

After the IMC composition has been injected into the mold cavity, itcures and adheres to the substrate and forms a coating. Thereafter, thefixed mold halves are parted and the coated article removed along withsprue 53, which contains a rim or projection formed by the mold runnercontainment shroud. The sprue is easily removed from the mold runner asthe projection formed in the containment shroud is generally flexible.Further coated articles can be produced because the IMC composition hasnot contaminated the injection apparatus, and no deposits of the IMCcomposition remain in the runner system.

FIGS. 26-29 show yet another mold modification to control IMC flow.Substrate 740 includes barrier 743 that includes a barrier rim ofsubstrate material 742, a substrate injection inlet area 744 and an IMCcomposition injection area 746. A containment flange 748 as describedabove is also shown. Again, while flange 748 is shown to completelysurround the area of substrate coated with coating 741, the flange mayonly partially surround the area to be coated based on the configurationof the workpiece and the flow characteristics of the mold. Furthermore,the substrate injection inlet area 744 is free of the IMC due to thepresence of barrier 743.

As shown in FIG. 27, barrier rim 742 extends around the perimeter ofsubstrate injection inlet area 744. Barrier rim 742 contains aprotrusion which is raised or elevated relative to the surface of theadjacent substrate, outside of the barrier rim perimeter. Typicalsubstrate injection orifices are generally round or cylindrical;accordingly, barrier rim 742 is also formed as a complementary shapearound the orifice and can be annular but generally can be any shape.

The height of the barrier rim and other portions of the substrate can bemeasured from one side of the substrate to the other, such as from theshow surface to the back or opposite surface, i.e., between thecorresponding mold halves, as described above. The rim height orthickness refers to a maximum height unless specifically stated. Theelevation or height of the barrier rim can also be measured from theshow surface to the distal end of the rim. The character Y in FIG. 28Billustrates the height of the barrier rim 742 which is substantially thesame throughout its width which is designated Z. The barrier rim heightY in conjunction with width Z is designed to substantially prevent IMCcomposition 741 from flowing into the substrate injection inlet area 744as shown in at least FIG. 28C. After the IMC composition is injectedonto substrate 740 surface at injection inlet area 746 in FIG. 27, thecoating spreads across the surface between a mold cavity surface and thesubstrate surface by compressing the substrate. Eventually, IMCcomposition 741 reaches the base of barrier rim 742 as shown in FIG. 28Cand attempts to flow up barrier rim 742 by compressing the width Z ofthe rim. Width Z is relatively thin and thus is sufficient to preventIMC composition 741 from flowing into substrate injection inlet area 744as shown in FIG. 28C at least because the rim width is relativelyincompressible and forms an IMC seal or barrier to coating flow.

Width Z can be made sufficiently thin so that IMC composition does notflow onto the rim itself, much less the substrate injection inlet area.Accordingly, the ratio of the barrier rim width Z to the thickness X ofthe substrate (as shown in FIG. 30A) adjacent to the barrier (measuredfrom the substrate front surface to the back surface) ranges generallyfrom about 0.1:1 to about 2:1, desirably from about 0.25:1 to about 1:1,and preferably from about 0.3:1 to about 0.8:1. The required compressiondifferential can vary depending on substrate composition, moldtemperature, and workpiece design, etc., and can be readily determinedthrough limited experimentation.

The differences in the height ratio between the barrier rim height Y(742 in FIG. 27) and the substrate thickness X are also sufficient toprevent IMC composition from breaching the substrate injection area ororifice, and ranges,generally from about 0.1:1 to about 5:1, desirablyfrom about 0.5:1 to about 2:1, and is preferably about 1:1.

FIGS. 28A-C illustrate a process for forming the substrate injectionorifice barrier and show a cross-sectional view through a portion of amold assembly similar to the apparatus shown in at least FIG. 1 anddescribed above. FIG. 28A shows a partial view of a mold cavity 40interposed between first and second mold halves 710 and 712respectively. In FIG. 28A, the mold cavity is also shown having barrierforming relief 721 including rim 722. A substrate-forming material 740is injected into mold cavity 40 at substrate injection inlet area 724when gate pin 720 is backed away from the entrance as shown in FIG. 28B.As described above, the gate pin is merely one example of a substrateinlet control.

During a typical molding cycle, gate pin 720 is backed away from inlet724 as shown in FIG. 28B, allowing substrate-forming material 740 toflow into mold cavity 40 to a predetermined level. Barrier 743 includingbarrier rim 742 is also formed with the substrate material. After asufficient amount of substrate forming material 740 has been injected,gate pin 720 is moved into a closed position as shown in FIG. 28C tostop the flow of substrate-forming material and for cosmetic purposes toleave a clean shut-off on the surface of the molded article.

After the substrate has cooled, achieves a suitable modulus, orotherwise is capable of accepting a liquid on its surface, the coatingcomposition is injected into the mold cavity. Upon Injection, IMCcomposition 741 flows across the surface of the substrate until itencounters barrier 743. Upon reaching barrier rim 742, IMC composition741 compresses the rim width against the mold cavity and ceases to flowinto the substrate inlet area or substrate injection orifice at leastbecause the relative compressibility of the substrate barrier rim widthalong the height thereof. Thus, as shown in FIG. 28C, IMC composition741 is prevented from reaching or flowing to gate pin 720 and passingbetween it and surrounding clearances.

FIG. 29 illustrates a barrier for a substrate injection apparatuswithout a gate pin. Accordingly, modifying the mold as described aboveprovides a barrier for substrate injection orifices even though a gatepin might not be utilized. IMC composition cannot access the substrateinjection inlet area due to the presence of the barrier.

Barrier rim 742 may have both varying heights and or widths and thus mayhave many different shapes or designs other than the barrier rim shownin FIGS. 28B, 28C, and 29 which has two walls with substantially equalheights formed at substantially perpendicular 90° angle to the substratemain surface and substantially constant width. FIG. 30A illustrates analternative barrier design having tapered rim 742 with varying height Yand width Z. The main portion of substrate 740 has a thickness or depthX. Rim 742 has one wall substantially perpendicular to the substratemain surface and a slanted wall at about a 45° angle. The upper,thinnest portion of the rim is substantially incompressible, and thusthe IMC composition substantially cannot flow into substrate injectioninlet area 744. FIGS. 30B-C illustrate other possible variations forbarrier rim design, showing a different tapered rim and a partiallyrounded rim. Design of the barrier rim is limited only by mold cavityconstraints wherein it is desirable to allow the substrate with barrierto be easily removed from the mold cavity after molding and coating.

Referring to FIG. 9, a mold for producing a plaque 200 is shown whichhas been designed to accept an IMC composition is shown. The mold cavitywidth is 30.5 cm, and its length is 52 cm. The mold has a hydraulic moldgate located in the center of the cavity for injection of a substrateand a tapered tab for the introduction of IMC composition onto the partsurface. The tab is located at the edge portion of the mold. Thethicknesses of tab and Section A are 0.003 mm, Section B is 0.0025 mm,Section C is 0.002 mm, and Section D is 0.0015 mm. The plaque has fourpanels in a horizontal plane on the left side of the part and fourpanels in a vertical plane on the right side of the part. The panels onthe horizontal plane on the right side of the part measure 15 cm longand 13 cm wide. The panels on the vertical plane measure 3.8 cm wide and52 cm long. The plaque does not have an IMC containment flange. The moldwas placed in a modified 771 Mg (850 ton) CINCINNATI MILACRON™ VISTA™injection molding machine. ABS resin heated to a temperature of 249° C.was injected into the mold cavity thus producing the plaque shown inFIG. 9 having sections A-D with the above described dimensions andthicknesses. The front of the plaque had a smooth surface and, thus, thebackside of the plaque shows the various thickness contour variations.After a delay or hold time of approximately 120 seconds, a STYLECOAT™coating composition was injected through the tab portion of the plaqueonto the front surface thereof. The chart below details how the coatingcomposition flowed onto the different sections of the plaque.

Amount of % of full Section A Section B Section C Section D IMC (cm³)IMC shot % fill/mm % fill/mm % fill/mm % fill/mm 0.52 25 75/0.02515/0.013 0/0 0/0 1.05 50 98/0.076 85/0.041   10/0.015 0/0

From the part surface area to be coated and the desired coatingthickness, an amount of 1.97 cm³ was determined capable of producing afull IMC shot to cover the entire plaque.

As can be seen from the chart, upon IMC injection onto the plaquesurface, the top left panel and the inside vertical panel (runnersection A) were preferentially coated when 25% of a full shot wasutilized. Thus, this example shows that Section A is an effective runnersection whereby the coating prefers to flow down the plaque alongSection A and out to the side thereof before flowing into thinnersections B, C, and D. When 50% of a full IMC shot was utilized, the IMCbegan to flow from Section A and B into Section C.

The plaque shown in FIG. 9 did not contain a containment flange. Whencoating levels above 50% of a full shot were utilized, the coatingcomposition leaked out of the mold cavity through the parting line.Thus, it was determined that a containment flange was needed to keep theIMC composition on the desired portion of substrate surface.

FIG. 10 shows a thermoplastic article 300 with a variety of substratethicknesses. The example parts were generated using a 45 Mg (50 ton)injection molding machine and 15 cm square steel mold, both of whichwere modified as described above. The substrate-forming material was aPET thermoplastic and the IMC was STYLECOAT™ primer. The moldtemperature was 121° C. with a 30 second delay time prior to IMCcomposition injection.

Sections E (0.29 cm thick), F (0.22 cm thick), and G (0.15 cm thick) arerepresentations of varying part thickness as shown by the chart below.Section H (0.15 cm thick) represents the tab design utilizing a thickermiddle section which facilitates a flow channel at the nozzle tip site.Section I (0.06 cm thick) represents the thin-sectioned containmentflange. An objective in designing and modifying a mold with thin andthick sections is to help channel flow of the IMC composition in adesirable fashion. This can be manifested in several ways which caninclude:

-   -   1. Channeling the IMC composition flow at the tab site        (Section H) which preferentially deposits the IMC composition        inside the mold parting line onto the part surface.    -   2. Channeling IMC composition flow to more critical areas        (Sections E, F, and G).    -   3. Restricting IMC composition flow along the periphery and/or        other mold portions to contain it on the desired surface of the        part and within the parting line (Section I).        The observed IMC coverage for the mold is as follows:

% of full Section E Section F Section G Section H Section I IMC shot %fill/mm % fill/mm % fill/mm % fill/mm % fill/mm 50 100/0.076  80/0.051 20/0.025 100/0.051 0/0 80 100/0.10 100/0.076  40/0.051 100/0.076 0/0100 100/0.10 100/0.076 100/0.076 100/0.10 0/0

The foregoing show that this enhanced flow mechanism has advantageswhich include preferential flow and deposition to selected regions on apart as a result of varying thickness and containing IMC composition onthe part surface through use of a thin-sectioned flange.

The present method relates to designing and producing a mold to be usedin connection with an injection molding machine so that the mold can beused to produce coated articles. The injection molding machine can beany of the known injection molding machines which has at least oneinjection apparatus to inject a molten material. The molding machineeither can include a separate apparatus for injecting IMC composition orcan include an integral system.

If a particular article has been manufactured previously, its existingmold is evaluated to obtain information on mold flow and anunderstanding of optimal running parameters for the existing moldincluding operating temperatures, pressures, type of resin used, moldtemperature based on the resin used, and fill patterns of the mold. Aflow analysis can be performed based on the natural configuration of theworkpiece to determine the likely flow of the substrate-forming materialand/or the IMC composition in the mold. The flow analysis can be used todetermine nozzle placement and whether flow enhancers or restrictors arenecessary or desirable.

Determining an optimal or preferred resin for the workpiece can involvea review of the specified resin chosen by the designers of the workpieceand/or the resin previously used for the workpiece (if it has beenmanufactured previously). Some resins are not processed at temperatureshigh enough to cure IMC compositions applied thereto (which generallycure at temperatures of from about 38° to about 149° C.). Thus, a resinmust be chosen which can work with a desired IMC composition yet satisfythe article design requirements; otherwise, mold heating may benecessary to cure the IMC composition.

The type of tool steel to be used for the mold can be determined;different types of tool steels have different properties which affecttheir machinability and performance. Additionally, mold design caninclude an optimization of the mold cavity surfaces. The surface of theworkpiece is a reflection of the condition of the surface of the moldcavity. A rough mold surface produces a workpiece with a dull or roughsurface. While this may be desirable for better adhesion for asubsequent out-of-mold coating operation, the surface finish or qualityof an IMC will be affected. Also, the surface finish impacts the releaseof the workpiece after the molding process is completed; a highlypolished mold cavity releases a coated workpiece better than anon-polished cavity. Additionally, if the mold cavity is to be chromed,the manner in which the mold is designed might need to be adjusted. (Achrome mold cavity provides excellent surface appearance, mold releaseand mold life; however, the chrome finish is relatively thin, thusmaking difficult modifications to or the repair of a chrome moldcavity.)

The mold can be designed so that mold runners, which direct the flow ofthe resin from the resin injection nozzle to the mold cavity, are spacedfrom the show surface of the workpiece. Due to the flow of substratethrough the substrate injector and injector heaters, the moldtemperature around the runner is hotter than other portions of the moldand, as described above, IMC composition flow is influenced by thecompressibility of the substrate resin which, in turn, is influenced byresin temperature; therefore, increased mold temperature near the runnersystem will influence the flow of the IMC composition. This can causecolor consistency problems and/or coverage problems. However, if basedon the workpiece design, a mold runner must be near a show surface, themold can be designed to include additional mold cooling near the runneror additional mold heating near other portions of the show surface so asto balance the mold temperature near the show surface and promote IMCcomposition flow is even and consistent.

Mold cooling and/or heating can be used to help solidify the resinand/or to control the resin flow. Mold cooling can be used to reduce thetime necessary to solidify the resin of the workpiece and to maintain adesired mold temperature, while mold heating can be used to prevent theresin from solidifying before the entire mold cavity is filled. This isespecially important in workpieces that are large and/or have intricateconfigurations. The typical injection molding facility has chilled plantwater used for mold cooling. A first type normally used for mold coolingis cooled by a cooling tower and produces water with a temperaturebetween 10 and 21° C. A second type utilizes evaporative coolers whichproduce cooling water between 21 and 32° C., although these may beelevated if the ambient temperature is above 32° C. A third type ofwater is heated water wherein the injection molding facility includescapabilities of heating water and supplying the heated water to themolding operation. The molding facility can also have oil heaters forheating oil which can be used to further control mold temperature. Themold can utilize one or more of these types of temperature controlledwater and/or oil to control the flow of IMC composition. The mold designcan utilize include adding cooling or heating lines to the mold halvesto allow for the desired flow of heated and/or cooled fluid.Furthermore, the molding system may need to be designed to accept one ormore of the types of heated and/or cooled fluid.

As stated above, IMC composition flow is based on the compressibility ofthe substrate which, in turn, is a function of substrate temperature. Asthe substrate cools, it begins to solidify, and solidified substrate isnot as compressible as is molten resin. Cooled or chilled water can beused to reduce mold temperatures in areas which are too hot, such as theportions of the mold near the runners. Hot spots in the mold can resultin areas of the substrate which are more compressible than other areaswhich are cooler. As a result, the IMC composition, which takes the pathof least resistance, flows to the more compressible hot spot. The hotspot can be addressed by adding cooling capabilities or utilizing coolerwater. The opposite is true for areas of the show surface which are lastto be coated. The resin in these areas may become too solidified beforethe coating composition has had a chance to completely coat the surface.Since these areas of the substrate have reduced compressibility, the IMCcomposition may stop flowing before reaching the end of the showsurface. Mold heating can slow the solidification of the substrate. Bydesigning the mold so that heated water and/or oil is pumped throughthese areas, the substrate remains in a more molten state and flow ofthe IMC composition is enhanced.

The mold can be designed to utilize one or more of these types oftemperature controlled water and/or oil to help cure the IMC. As statedabove, the IMC is cured based on heat and, more particularly, on theheat of the substrate. Therefore, designing the mold to include heatingand/or cooling lines in the mold portion adjacent the show surface canpromote curing of the IMC by optimizing the mold temperature based onthe resin and IMC used.

A flow modeling or analysis can be performed on a preexisting moldpreviously used to produce the molded article in question and/or theworkpiece design to determine the optimal design of the mold in view ofthe flow characteristics of the materials and the potential to enhanceand/or restrict flow. The design relates to obtaining a desired flowpattern of the IMC composition Including obtaining complete coverage ofthe show surface, minimizing flow lines (especially with metalliccoatings), and minimizing undesired flow of the IMC. The flow analysisdetermines the optimal location or placement of the IMC nozzle bybreaking the show surface into grids and can utilize computer technology(e.g., flow modeling software) to determine the IMC composition flowbased on the characteristics of the mold or the design of the moldedarticle. The flow analysis can also determine if more than one IMCcomposition nozzle is necessary or desirable. The flow analysis also canbe performed before or after the mold design is complete.

The design of the article relative to the show surface influencesmodifications made to the mold. These modifications relate to obtaininga desired flow pattern of the IMC composition, including obtainingcomplete coverage of the show surface, minimizing flow lines (especiallywith metallic coatings), and minimizing undesired flow.

If the show surface includes ribs, bosses (internal openings), orintricate surfaces, the IMC composition might not flow as desired. Thedesign can include addition of a mold runner which can direct and/orpromote flow. By creating areas of increased part thickness, flow can beenhanced by the increased compressibility of the substrate. In general,changes to the article design can be made which increase thecompressibility of the substrate to promote or direct IMC compositionflow.

Alternatively, if the show surface is near a parting line, a core, aslide, a shutoff, an internal parting line or an ejector pin, the molddesign might need to incorporate an element designed to restrict IMCcomposition flow, which is introduced into the mold cavity undersignificant pressure and follows the path of least resistance.Therefore, if the show surface includes any one of these moldcomponents, the IMC composition can exit the show surface through thesecomponents which prevents the IMC from fully coating the show surfaceand can affect the function of the mold. Therefore, the mold design isevaluated to determine if the IMC composition will flow into these moldcomponents or locations. The IMC which is applied under pressure willenter any opening which is greater than about 0.025 mm. Ejector or corepins, for example, typically have a clearance of 0.05 or 0.075 mm and,therefore, if the show surface includes an ejector or core pin, the IMCcomposition can enter the ejector or core pin cavity and eventuallyprevent operation of the ejector or core pin. The same is true forparting lines, cores, slides, shutoffs, and internal parting lines. Ifit is determined that one of these types of components needs to bepresent on or near a show surface, the design of the article isevaluated to determine whether it includes an element designed such thatthe flow of IMC composition into or out of these areas is prevented. Forexample, if a given molded article naturally includes a flange aroundthe show surface which coincides with the parting line, no modificationmay be necessary. The naturally present flange can act to restrict flow.However, if the natural configuration of the article does not includesuch a feature, the design of the mold can be adjusted to incorporateflow restricting features that prevent unwanted flow of IMC composition.

Based on experimentation and/or flow analysis or modeling of the mold,an optimum position of the IMC injector nozzle(s) can be determined, andthe mold designed to include an opening or port for each nozzle. Once adesired location is determined, additional flow modeling analysis can beperformed to confirm or modify this location.

The nozzle preferably is near the perimeter of the mold itself and on anedge of the show surface. With respect to the position relative to themold, the IMC composition nozzle is a replaceable component of the moldand, therefore, access to the nozzle helps with maintenance of the mold.Turning to the position relative to the show surface, an IMC nozzle onthe edge of the show surface can minimize the visual imperfectionsassociated with the molding process. Flow analysis also can be used todetermine whether more than one IMC composition injector is needed andto determine the optimal location of the multiple injectors. Moreparticularly, the IMC composition preferably is directed into the moldcavity in such a way that all portions of the show surface are evenlycoated without the appearance of flow lines. The flow analysisdetermines the optimal placement of the IMC composition injector(s) toobtain the desired flow. Laminar flow across the show surface ispreferred. Further, nozzle placement can be evaluated in connection withflow enhancers or restricters described above to determine the optimalnozzle arrangement.

Referring to FIGS. 31A-D, four different styles of nozzle arrangementsare shown. FIG. 31A depicts a smaller, less complicated part 530 whereina single nozzle 62 is sufficient to coat the entire show surface 532. Inthis example, the nozzle is placed in the center of the show surface andproduces laminar flow 534 about nozzle 62 in all directions. FIGS. 31B-Ddepict a larger and/or more intricate part 536 with a show surface 538where a single nozzle is not sufficient to produce the level of flownecessary to completely coat the show surface. In FIG. 31B, two nozzles62 a and 62 b are shown on either side of show surface 538. The resultis creation of two separate IMC flows 540 and 542 which flow toward eachother and meet at the middle of the show surface at a knit line 544.Furthermore, as the separate flows reach each other, pockets 546 and 548are formed. The result is that the knit line is visible in the completedworkpiece and pockets 546 and 548 are not coated. FIG. 31C shows a twonozzle arrangement preferred over the one shown in FIG. 31B. In thisrespect, nozzles 62 c and 62 d are spaced apart on the same side of theshow surface. As a result, a unified single laminar flow 550 is producedby the two nozzles. In this arrangement, flow begins on one side of theshow surface and flows together to the opposite side wherein no knitline is produced and air pockets are minimized. Furthermore, any airpockets produced are adjacent the edge of the show surface which may beacceptable. Referring to FIG. 31D, if more flow is necessary, the moldcan be modified to include a three nozzle arrangement 62 e, 62 f and 62g; however, the three nozzles preferably are still positioned so that asingle laminar flow is produced. If necessary, the flow of theindividual nozzles 62 e-g, can be varied to provide a desired flow. Inthis respect, nozzle 62 f can receive 75% of the flow while nozzles 62 eand 62 g receive together only 25%. While it has been found that the useof three nozzles has been sufficient to obtain the desired flow, morenozzles could be utilized. In addition, flow enhancers described aboveincluding mold heating and/or cooling could be used in connection withthe multiple nozzle arrangements to achieve desired flow.

The size and configuration of the actual nozzle (including innerdiameter) is based on the volume of the IMC composition necessary tocoat the show surface. Preferably, the nozzle is mounted so that it canbe removed for cleaning and/or replacement, and the nozzle tip isconfigured to correspond with the shape of the cavity wall.

Designing the mold also can include an evaluation of and modificationsto the resin injector(s) to ensure that IMC composition does not enterthe resin injector(s). The location of the resin nozzle in relation tothe show surface is the primary consideration. If the resin nozzle isnot within or sufficiently near the show surface, incorporation of flowrestricters likely is unnecessary. If the nozzle is within the range offlow of the IMC composition, the design of the nozzle preferably isevaluated to ensure that IMC composition does not enter. If it isdetermined that the IMC can enter the resin nozzle, the mold design canincorporate one of the several discussed containment flanges to preventIMC composition from entering the resin injector. In addition, the molddesign can include cooling enhancements to reduce the elevated moldtemperature which may be present near the nozzle.

The present method can include running a series of experiments and/orperforming a flow analysis with the new mold and a specific polymericmaterial to optimize the process. In designing a mold, determining theultimate machine conditions of the system in connection with a specificmold, a specific substrate material, and a specific IMC composition canbe important. In setting up the mold, a large number of variables mustbe interrelated to produce acceptable parts in a commercially acceptableamount of time. Pressures, times, and other settings of the injectionmachine vary with the shape of the part being manufactured and/or thepolymeric material being used. To optimize these and other criticaloperating parameters of the injection process, the volume of a givenmold may be calculated and, based on this calculation and the density ofthe substrate-forming material, charge size can be determined. Differingmachine variables can be tried until an optimum, complete filling of themold in a minimum time, is determined. Preferably in these experiments,the mold is fitted with one or more transducers and/or sensors whichmeasure pressure and/or temperature while various machine variables(e.g., injection speeds and pressures) are altered.

1. A method for designing a mold for use in a molding system thatincludes (i) a dispensing apparatus for a coating composition, (ii) amolding machine that comprises first and second mold sections, said moldsections being operable between open and closed conditions and, in saidclosed condition, defining a mold cavity in which a molded articlehaving at least one surface to be coated can be formed, said dispensingapparatus being in fluid communication with said molding machine so thatsaid coating composition can be introduced into said mold cavity throughone or more injection nozzles that engage with one or more access portsin one or both of said mold sections, said method comprising: a)evaluating said article, including said at least one surface; b)modeling the flow of said coating composition across said at least onesurface when said article is being molded within said mold cavity; c)determining one or more preferred introduction points for said coatingcomposition; and d) designing said mold sections in response to saidmodeling so that one or both comprises (1) said one or more access portspositioned at said one or more preferred introduction points and (2) aflow control which utilizes substrate compressibility to control theflow of said coating composition across said at least one surface, saidmold sections being capable of being incorporated into said moldingmachine and used in said molding system.
 2. The method of claim 1further comprising the step of determining a preferred material forforming said article.
 3. The method of claim 1 further comprising thestep of modifying said coating composition flow by determining anoptimal temperature for at least one of said mold and said at least onesurface of said article.
 4. The method of claim 1 wherein said flowcontrol includes a mold cavity shape comprising at least one elementthat modifies the flow of said coating composition.
 5. The method ofclaim 1 wherein said flow control includes at least one of a moldrunner, a temperature apparatus to adjust the temperature of said moldin order to change the temperature of at least a portion of said moldcavity, and a flange.
 6. The method of claim 1 wherein said moldincludes at least one sensor for measuring at least one of machine andmold variables.
 7. The method of claim 1 wherein said molding systemcomprises a plurality of injection nozzles.
 8. The method of claim 7further comprising positioning said plurality of injection nozzles so asto provide laminar flow of said coating composition across said at leastone surface.
 9. The method of claim 1 further comprising the step ofdesigning at least one injector.
 10. The method of claim 1 furthercomprising analyzing said article so as to determine an optimal molddesign.
 11. The method of claim 10 wherein said analyzing step involvesperforming a flow modeling analysis of said mold design so as todetermine other machine or mold parameters.
 12. The method of claim 1further comprising determining an optimized position for said flowcontrol.
 13. The method of claim 1 further comprising utilizing theresulting design to manufacture said mold sections and installing saidmold sections in said molding machine.
 14. The method of claim 13further comprising molding a first molded article in said mold cavity.15. The method of claim 14 further comprising modifying said mold cavityto include at least one of a mold runner, a temperature apparatus and aflow restricting flange.
 16. The method of claim 14 further comprisingreviewing said first molded article and adjusting said flow control tomodify the flow of said coating composition across said at least onesurface.
 17. The method of claim 16 wherein said flow control includesat least one of a mold runner, a temperature apparatus to adjust thetemperature of said mold in order to change the temperature of at leasta portion of said mold cavity, and a flange.
 18. The method of claim 14further comprising determining optimized positions for one or moreadditional flow controls and installing said one or more additional flowcontrols at said optimized positions.
 19. The method of claim 1 furthercomprising determining a preferred coating composition.